1. Field of the Invention
The present invention relates to the use of fuel additives in liquid fuels to improve the efficiency of fuel-burning devices such as engines and furnaces. More specifically, the present invention relates to high molecular weight fuel additives that change the physical properties of fuel under the dynamic conditions of fuel atomization and vaporization. The invention also relates to additive concentrates and fuel compositions containing the additive.
2. Description of the Related Art
Sixty percent of the energy in gasoline is not converted to useful mechanical energy in the combustion process. Chemists cannot safely put more energy in gasoline. Engineers are designing changes in the induction system, cylinder head and piston of engines to improve engine efficiency; however, their options are limited.
Known fuel additives, many of which are commercially available under several well-known brand names, enhance the performance of the fuels to which they are added only to the extent that the additives themselves are fuels. In addition, prior art fuel additives are claimed to provide lubrication to fuel and thereby reduce the friction in an engine; however, none of the prior art fuel additives are known to adapt the physical properties of the fuel in order to enhance engine performance.
Low concentrations of relatively high molecular weight polymers, such as high molecular weight polyisobutylene, are known to reduce flow turbulence and have been used as drag-reducing additives. See U.S. Pat. Nos. 4,546,748 and 4,837,249. High molecular weight alpha-olefins are known as anti-misting additives for fuels to reduce flammability of fuel sprays occurring during aircraft crashes. See U.S. Pat. No. 4,789,383, assigned to the assignee of the present application, the disclosure of which defines high molecular weight polymers as including Oppanol.RTM. B200 (polyisobutylene having a molecular weight of about 4 million daltons) and very high molecular weight polymers as those above 5 million daltons, and is incorporated herein by reference. However, the use of high molecular weight polymers to change the physical properties of fuel and improve combustion efficiency has not heretofore been suggested.